Diane Sawyer on the Pine Ridge Indian Reservation

Diane Sawyer on the Pine Ridge Indian Reservation

Diane Sawyer visiting the neighborhood of Tashina Iron Horse, 5, on the Pine Ridge Indian Reservation. Tune in Friday at 10 p.m. ET for a special "20/20" with Diane Sawyer, "A Hidden America: Children of the Plains"

Jill Belsley/ABC News

Diane Sawyer on the Pine Ridge Indian Reservation

Diane Sawyer visiting the neighborhood of Tashina Iron Horse, 5, on the Pine Ridge Indian Reservation. Tune in Friday at 10 p.m. ET for a special "20/20" with Diane Sawyer, "A Hidden America: Children of the Plains"

Jill Belsley/ABC News

Diane Sawyer on the Pine Ridge Indian Reservation

Tashina and her mother Bobbi sharing family photos with Diane Sawyer.

Jill Belsley/ABC News

Diane Sawyer on the Pine Ridge Indian Reservation

Growing up in one of the poorest counties in America – The Pine Ridge Indian Reservation – takes resilience.